This invention relates generally to gas turbine engines and more particularly, to the oil supply and scavenge systems used within gas turbine engines.
A gas turbine engine typically includes at least one bearing assembly that rotatably supports a shaft. The bearing assembly is lubricated with oil, and heat from other engine components is absorbed and dissipated by the oil. Accordingly, bearing assemblies are housed within sumps that typically include an oil supply jet that supplies lubricating oil under pressure from an external pump to the bearing assemblies, and an external scavenge pump that removes lubricating oil from the sump. In at least some know engines, the scavenge pump channels the return oil through a heat exchanger prior to returning the oil to a tank or reservoir.
Within at least some applications, such as aircraft propulsion systems, interruption of the oil supply from the usual main oil pump of the engine may cause seizure of the bearing assembly, loss of engine thrust, engine fire and/or damage to the aircraft. Known methods for supplying oil to, and scavenging oil from, the various bearing sumps and gearboxes utilize a multi-element positive displacement pump. Known pumps usually are spline driven by the engine gearbox and include a supply element and a plurality of scavenge elements coupled to single or dual shafts internal to the pump. Internal failures in the pump, or the loss of drive power to the gearbox may result in the loss of supply flow of oil lubricants to the bearing, and/or loss of scavenge flow, which over time, can result in sump flooding and possible fire.